Apparatus and method for joining layers of materials

ABSTRACT

A method and apparatus for joining multiple layers of materials using an ultrasonic welding apparatus. The ultrasonic welding apparatus utilizes a sonotrode to perform a weld between at least the top and intermediate layer of the multi-layer member. Then, either the multi-layer member or the ultrasonic welding apparatus is rotated such that the bottom layer is positioned adjacent the sonotrode wherein the sonotrode forms a weld between at least the bottom layer and intermediate layer of the multi-layer member. The apparatus includes an ultrasonic welding gun having a C-shape frame including a base portion and a head portion. An ultrasonic welding device, including a sonotrode, is secured to the head portion and an anvil secured to the base portion. The ultrasonic welding gun is connected to a robot operative to position the ultrasonic welding gun to perform the welding operation.

BACKGROUND OF INVENTION

[0001] The present invention relates generally to ultrasonic welding andmore particularly to welding at least two layers of material together.

[0002] Ultrasonic welding of dissimilar materials is known. In today'smanufacturing society, lightweight composite materials are desirable andoften substituted in an attempt to build lighter and stronger products.Such manufacturing often requires the joining of several layers oflightweight materials formed of various combinations and alloys, such asaluminum and magnesium. In a typical automotive application, the twoaluminum layers sandwich a magnesium layer between them. These layersmust be connected to one another or, put succinctly, welded together toform a single unitary component.

[0003] As known with ultrasonic welding, the strength and degree of weldpenetration decreases the further the distance from the sonotrode tip.Accordingly, when welding multiple layers of material the weld lessensin strength at the subsequent or lower interfaces; i.e., the weld at theinterfaces between the lower layers is not as strong as the weld at theinterface between the top and immediately adjacent layer.

SUMMARY OF INVENTION

[0004] Accordingly, the present invention is an ultrasonic weldingapparatus and method for joining layers of materials. The methodincludes the steps of clamping multiple layers of materials between asonotrode and an anvil of an ultrasonic welding apparatus. Once clamped,the ultrasonic welding apparatus, specifically the sonotrode, forms aweld between at least the top and intermediate layer of the multi-layermember, wherein the first or top layer is adjacent the sonotrode. Then,rotating either the multi-layer member or the ultrasonic weldingapparatus wherein the bottom layer of the multi-layer member is nowpositioned adjacent the sonotrode. Once the sonotrode is positionedadjacent the bottom or lower layer, the layers are once again clampedand a weld is formed between at least the bottom and intermediate layer.

[0005] In an additional embodiment, the intermediate layer may include aplurality of layers. In some instances, additional layers are placed onand overlay the outer layers of the multi-layer member. These layers arealso ultrasonically welded thereto. This process results in anultrasonically welded multi-layer composite member.

[0006] The ultrasonic welding assembly includes an ultrasonic weldinggun having a C-shape frame including a base portion and a head portionjoined together to form the C-shape frame. The C-shape frame furtherdefining a throat area between the base portion and head portion. Anultrasonic welding device, including a sonotrode is secured to the headportion. Secured to the base portion is an anvil. The ultrasonic weldingassembly further includes a robot connected to the ultrasonic weldinggun. The robot operates to position and rotate the ultrasonic weldinggun to perform the welding operation.

[0007] In a further embodiment, an additional ultrasonic welding devicereplaces the anvil of the ultrasonic welding gun positioned on the baseportion. Accordingly, the ultrasonic welding gun welds from either sideof the multi-layer member without removing and rotating either themulti-layer member or the ultrasonic welding gun.

[0008] In an additional embodiment, the anvil and sonotrode assembly arepositioned on separate supports or frames. Accordingly, both the anviland sonotrode move independently to a specific location to perform awelding operation rather than moving the multi-layer member.

BRIEF DESCRIPTION OF DRAWINGS

[0009]FIG. 1 is a schematic view of an ultrasonic welding apparatus thatcan be used with the method of the present invention;

[0010]FIG. 2 is a schematic view illustrating a multi-layer workpieceformed of multiple layers of material welded together in accordance withthe method of the present invention;

[0011]FIG. 3 is a schematic view of a robot attached to and operative tomove and position an ultrasonic welding gun;

[0012]FIG. 4 is an enlarged side view of the ultrasonic welding gun ofFIG. 3;

[0013]FIG. 5 is an enlarged side view of an alternative embodiment of anultrasonic welding gun in accordance with the present invention; and

[0014]FIG. 6 is a schematic view of a further embodiment of anultrasonic welding apparatus in accordance with the present invention.

DETAILED DESCRIPTION

[0015]FIG. 1 shows an ultrasonic welding apparatus 10 for use inaccordance with the method of the present invention. The ultrasonicwelding apparatus 10 includes a reed 12 and sonotrode 14 mounted thereonfor movement in a side-to-side or horizontal direction of vibration,shown by the arrow 16. The reed 12 with the mounted sonotrode 14 alsomoves in a vertical manner, shown by the arrow 18, and in cooperationwith an anvil 20 clamps multiple layers of material together prior towelding the layers together to form a multi-layer member 24. As usedherein, the term sonotrode generally refers to the tool attached to thereed 12. In many cases, the sonotrode 14 also includes replaceable tip.Accordingly, the sonotrode 14 is the gripping tool attached to the endof the reed 12. A transducer 22 operates through a wedge 23 thattransfers the vibrations from the transducer 22 to the reed 12.

[0016] As shown in FIG. 2, in one embodiment the multi-layer member 24includes a top or upper layer 26, an inner layer 28, and a bottom orlower layer 30. Once the multi-layer member 24 is clamped, a transducer22 vibrates the reed 12 at a high frequency to impart energy to themulti-layer member 24 at a location between the sonotrode 14 and anvil20. Positioning the sonotrode 14 adjacent the top or upper layer 26causes the energy from the vibrating sonotrode to form a bond or weld 32at at least the interface 27 between the top or upper layer 26 and theinner layer 28 in accordance with known ultrasonic welding processes.

[0017] The invention includes a method for joining multiple layers ofmaterial utilizing a stitch-weld technique that forms successive welds32 between the top or upper layer 26 or the bottom or lower layer 30 andthe inner layer 28 by applying ultrasonic vibrations to each side of themulti-layer member 24. In one embodiment, typically used for anautomotive application, a three-layer combination of aluminum andmagnesium layers forms the multi-layer member 24. Wherein magnesiumforms the inner layer 28 that is sandwiched between the top 26 andbottom 30 layers formed of aluminum. As illustrated in FIG. 2,successive welds 32 are formed between the inner 28 magnesium layer andthe top and bottom 26, 30 aluminum layers.

[0018] In one embodiment, physically rotating or turning over either themulti-layer member 24 or the ultrasonic welding apparatus 10accomplishes the stitch welding process. Specifically the methodincludes the steps of clamping the respective inner 28 and outer 26, 30layers of the multi-layer member 24 between the sonotrode 14 and theanvil 20. As depicted in FIG. 1, the top or upper layer 26 is placedadjacent to and contacts the sonotrode 14 when the multi-layer member 24is clamped within the ultrasonic welding apparatus 10. The sonotrode 14than vibrates to transfer ultrasonic energy to the multi-layer member 24to form a weld 32 primarily between the top or upper layer 26, incontact with the sonotrode 14 and the inner layer 28.

[0019] Upon completion of the welding process, the ultrasonic weldingapparatus is unclamped and either the multi-layer member 24 or theultrasonic welding apparatus 10 is rotated or turned over such that thelower or bottom layer 30 is adjacent to the sonotrode 14. The ultrasonicwelding apparatus closes once again to clamp the multi-layer member 24between the sonotrode 14 and the anvil 20. Once clamped, the sonotrode14, in contact with the bottom or lower layer 30, vibrates to transferultrasonic energy to form a weld 32 primarily between the bottom orlower layer 30 and the inner layer 28.

[0020] Accordingly, welds 32 applied from alternating sides of themulti-layer member 24 join all three layers of the multi-layer member24. As shown in FIG. 2, the welds 32 are laterally offset from oneanother. FIG. 2 shows the weld zone 42 formed primarily between eitherthe top or upper layer 26 or the bottom or lower layer 30 and the innerlayer 28. It is known to one of skill in the art, however, that the weldzone 42, depending upon the amount of vibrational energy transferredfrom the sonotrode 14 to the individual layers, may extend or penetratefrom the top or upper layer 26 through the inner layer 28 and form anadditional weld at the interface 29 between the inner layer 28 and thebottom or lower layer 30. Increasing the penetration depth of the weld32 typically results in an increase in the strength of the multi-layermember 24 as the weld 32 extends through both interfaces 27,29 of thetop and bottom layers 26, 30 and the inner layer 28.

[0021] Additionally, the present invention contemplates welding morethan three layers with the above-identified method. This is accomplishedin one of several ways, one of which includes generating sufficientultrasonic energy such that a weld is formed between and penetratesthrough multiple layers of the multi-layer member 24. For instance, in afour-layer assembly, the weld 32 extends or penetrates through the firstand second layers and into the third layer to join the first, second andthird layers at the interfaces between the first and second layer andthe second and third layer. Accordingly, as set forth above, once thewelding process is completed either the multi-layer member 24 or theultrasonic welding apparatus rotates. After which, a weld 32 is formedthat extends from the fourth layer through the third and second layersagain forming a weld at the interfaces between the fourth and thirdlayer and the third and second layer.

[0022] Pursuant to the invention, additional layers may be added byplacing them on the already welded layers. For instance, starting with athree-layer multi-layer member a fourth and fifth layer may be weldedthereto. Accordingly, a plurality of layers of similar or dissimilarmaterials may be welded together to form a composite multi-layer member.

[0023] A further aspect of the inventive method includes the use of twooppositely facing sonotrodes, each operative to form a weld. As setforth more fully below, each sonotrode serves as an anvil for theopposite sonotrode depending upon which sonotrode is vibrating to impartvibrational energy to the multi-layer member to form a weld. Inaccordance with the inventive method, the two sonotrodes clamp themultiple layers between them. Initially, one of the sonotrodes vibrateswhile the other sonotrode remains stationary and acts as an anvil inorder to form a weld between the top or upper layer, adjacent to thesonotrode, and the inner layer. Upon completion of the initial weldingprocess, the first sonotrode remains stationary, while the oppositesonotrode vibrates to form a weld between the bottom layer, adjacent theopposite or second sonotrode, and the inner layer.

[0024] Accordingly, welds applied from alternating sides join the threelayers of the multi-layer member. Prior to forming the second weld, asset forth above, the sonotrodes may be unclamped from the multi-layermember and repositioned such that the second weld is laterally offsetfrom the first weld.

[0025] Depicted in FIG. 3 is an embodiment of an ultrasonic weldingassembly 44 for use with a method of the present invention. Theultrasonic welding assembly 44 includes a robot, seen generally at 46,supporting an ultrasonic welding gun 48. A base 50 that includes amovable member 52 rotatably supported on the base 50 supports the robot46 for movement in the direction indicated by the arrow 54. A first arm56 is pivotally connected to the movable member 52 at a first pivotjoint 58 for movement in the direction indicated by the arrow 60. Asecond pivot joint 62 connects the first arm 56 with a second arm 64 andenables movement in the direction indicated by the arrow 66. A thirdpivot joint 68 connects a third arm 70 to the second arm 64 and enablesmovement in the direction indicated by the arrow 72. A rotation joint 74disposed on the third arm 70 enables rotation of the member a fourth andfifth layer may be welded thereto. Accordingly, a plurality of layers ofsimilar or dissimilar materials may be welded together to form acomposite multi-layer member.

[0026] A further aspect of the inventive method includes the use of twooppositely facing sonotrodes, each operative to form a weld. As setforth more fully below, each sonotrode serves as an anvil for theopposite sonotrode depending upon which sonotrode is vibrating to impartvibrational energy to the multi-layer member to form a weld. Inaccordance with the inventive method, the two sonotrodes clamp themultiple layers between them. Initially, one of the sonotrodes vibrateswhile the other sonotrode remains stationary and acts as an anvil inorder to form a weld between the top or upper layer, adjacent to thesonotrode, and the inner layer. Upon completion of the initial weldingprocess, the first sonotrode remains stationary, while the oppositesonotrode vibrates to form a weld between the bottom layer, adjacent theopposite or second sonotrode, and the inner layer.

[0027] Accordingly, welds applied from alternating sides join the threelayers of the multi-layer member. Prior to forming the second weld, asset forth above, the sonotrodes may be unclamped from the multi-layermember and repositioned such that the second weld is laterally offsetfrom the first weld.

[0028] Depicted in FIG. 3 is an embodiment of an ultrasonic weldingassembly 44 for use with a method of the present invention. Theultrasonic welding assembly 44 includes a robot, seen generally at 46,supporting an ultrasonic welding gun 48. A base 50 that includes amovable member 52 rotatably supported on the base 50 supports the robot46 for movement in the direction indicated by the arrow 54. A first arm56 is pivotally connected to the movable member 52 at a first pivotjoint 58 for movement in the direction indicated by the arrow 60. Asecond pivot joint 62 connects the first arm 56 with a second arm 64 andenables movement in the direction indicated by the arrow 66. A thirdpivot joint 68 connects a third arm 70 to the second arm 64 and enablesmovement in the direction indicated by the arrow 72. A rotation joint 74disposed on the third arm 70 enables rotation of the third arm 70 aboutthe longitudinal axis of the third arm 70 in the direction shown by thearrow 76.

[0029] A control unit 78, including a processing unit for receiving andsending control information, operates to position the ultrasonic weldinggun 48 to perform the welding operation. The control unit 78 alsocontrols operation of the ultrasonic welding gun 48. Accordingly, theultrasonic welding assembly 44 is programmable to perform a variety ofwelding tasks in various positions on various types of materials.

[0030] Turning now to FIG. 4, there is shown the ultrasonic welding gun48 in greater detail. As shown, the ultrasonic welding gun 48 has aC-shape frame 80 including a base portion 82 and a head portion 84interconnected by a column portion 86. The C-shape frame defines athroat 88 into which the multiple layers are inserted. The depth of thethroat 88 limits the location of the welds on the multi-layer member.For example, a deeper throat 88 enables welding the multi-layer memberat a greater the distance from the peripheral edge thereof.

[0031] An anvil 90 is secured on the C-shape frame 80 via threadedfasteners 92. The anvil 90 may also form an integral part of the baseportion 82 wherein only the tip portion 94 of the anvil 90 is removablysecured to the base portion 82.

[0032] Mounted for reciprocal movement on the head portion 84 of theC-shape frame 80 is an ultrasonic welding device 95, including asonotrode 112 mounted to a reed 96. In the present instance, the reed 96is slidably secured within a guide or support bracket 98 secured to thehead portion 84. A reed support 100 further supports and guides theupper end 97 of the reed 96. A cylinder support bracket 103 supports aclamp cylinder 102, either hydraulic or pneumatic type, on the headportion 84. In addition, other types of drive mechanisms such as leadscrews or servos may also be used. A coupling 106 connects a rod member104 of the clamp cylinder 102 to the upper end 97 of the reed 96. Inoperation, the clamp cylinder 102 urges the sonotrode 96 inward towardthe anvil 90 to clamp the multiple layers between the anvil 90 andsonotrode 96. Once clamped, a transducer 108 vibrates a wedge 110connected to the reed 96 to impart vibrational movement to the sonotrodetip 112 to perform the welding operation. This arrangement is similar tothat shown in FIG. 1.

[0033] Turning now to FIG. 5, there is shown an alternate embodiment ofand ultrasonic welding assembly 114 for use with the method of thepresent invention. The ultrasonic welding assembly 114 includes aC-shape frame 116 supporting ultrasonic welding devices 117, includingsonotrodes 118, mounted on both the head portion 120 and base portion122 of the C-shape frame 116. In all other respects, the mountingarrangement and operation of the ultrasonic welding devices 117,including the sonotrodes 118, is identical to the ultrasonic weldingdevice 95 of the previous embodiment.

[0034] In this alternative embodiment, the two sonotrodes 118alternately serve as the anvil for the opposite sonotrode 118 during thewelding process. For example, during the welding process the twosonotrodes come together to clamp the multiple layers in position forwelding. One of the sonotrodes 118 remains stationary and functions asan anvil while the opposite sonotrode vibrates to form a weld. After thefirst sonotrode has completed the welding process, it remains stationaryand the opposite sonotrode is energized to form a weld on the oppositeside of the multi-layer member across from the first weld. The processcan use the same power supply for both guns.

[0035] In addition, the sonotrodes may be unclamped from the multi-layermember and shifted, to a new position prior to energizing the oppositesonotrode. The sonotrodes are then re-clamped to the multi-layer memberwherein the sonotrode that formed the previous weld now functions as theanvil and the sonotrode performing the function of the anvil nowvibrates to form a weld. Accordingly, such a device joins multiplelayers of material with welds applied from alternating sides and invarious positions, including offset from those on the opposite surface,without the need to rotate either the ultrasonic welding gun or themulti-layer member.

[0036] A further embodiment of the present invention is illustrated inFIG. 6. Shown therein is a modular ultrasonic welding apparatus, seengenerally at 128, for welding or forming a weld between respectiveflange portions 130,131 of first 132 and second 134 workpieces. Theapparatus differs from the embodiments disclosed above in that therespective anvil 136 and sonotrode 138 are mounted to individual frameor support members 140, 142.

[0037] The sonotrode 138 is mounted for reciprocal movement on anupright support member 144 of the frame 142. A power cylinder 148 drivesa plurality of linkage bars 146 pivotally connected to the frame 142.Accordingly, the power cylinder 148 operates to move the sonotrode 138in a reciprocal manner on the frame 142. Thus, the sonotrode 138 movesbetween a disengaged position, where the sonotrode 138 is separate fromthe flange portion 130 and an engaged position where the sonotrode 138contacts the flange portion 130. While shown herein utilizing linkagebars 146 and a power cylinder 148 to reciprocally move the sonotrode138, any arrangement suitable for moving the sonotrode 138 in areciprocal manner such that it cooperates with the anvil 136 to clampthe flange portions 130,131 prior to the welding operation is within thescope of this invention.

[0038] A linkage bar 150 pivotally mounts the anvil 136 to the framemember 140. A power cylinder 152 pivotally connected to the frame 140connects to the linkage bar 150. The power cylinder 152 operates to movethe anvil 136 between a disengaged position, wherein the anvil 136 isseparated from the flange portion 131 and an engaged position whereinthe anvil 136 contacts the flange portion 131 of the second workpiece134 and supports both of the flange portions 130, 131 during theultrasonic welding operation.

[0039] A control unit 154 connects the respective power cylinders 148,152 and the transducer 133 through control lines 156 and operates tocontrol operation of the modular ultrasonic welding apparatus 128. Thecontrol unit 154 may include sensors and feedback loop technology.

[0040] In accordance with the present embodiment, the first and secondworkpieces 132,134 are placed in a predetermined position prior to thewelding operation, typically, within and supported by a fixture or jig.The anvil 136 and sonotrode 138 move to their respective engagedpositions located on opposite sides of the individual flange portions130,131. The sonotrode 138 is pressed against the flange portion 130 ofthe second workpiece 134 and correspondingly clamps the flange potion130 against the opposite flange portion 131 of the first workpiece 132supported by the anvil 136. The sonotrode 138 vibrates to produce aweld. Once the weld is completed, the anvil 136 and sonotrode 138 areretracted to their respective disengaged positions.

[0041] The ultrasonic welding assemblies shown herein utilize an anvilthat supports the various workpieces during the welding operation. Insome circumstances, however, the mass of the workpiece acts as the anvilthereby eliminating the need for an anvil. For instance, when welding asmall or thin workpiece to any portion of a large member or frame, themass of the member or frame may be sufficient such that only thesonotrode is used. That is, no anvil is required when the mass of thelarger workpiece is sufficient to resist vibration of the sonotrode.Accordingly, the sonotrode vibrates the smaller workpiece on the largerworkpiece to weld it thereto. The supporting fixture pr jig may act asan anvil and hold the bottom part or first workpiece 132 fixed.

[0042] Specifically, the sonotrode holds the smaller workpiece againstthe larger workpiece. Energizing the sonotrode welds the smallerworkpiece to the larger workpiece. Accordingly, this eliminates the needfor the anvil and enables welding of small and dissimilar parts to alarger workpiece such as an automotive frame. For instance, a groundclip or wire is easily welded to an automotive frame member despite anydissimilarity of the materials between the two pieces.

[0043] In addition, such a method and apparatus enables ultrasonicwelding of pre-painted or anodized workpieces. The vibrational energyimparted to the various workpieces operates to wear or rub away theimpurities from the surface of the adjacent workpieces until ametal-to-metal contact is reached. Accordingly, such ultrasonic weldingenables the joinder of dissimilar or other coated materials.

[0044] Thus, the present invention provides a method for joiningdissimilar workpieces such as aluminum and magnesium by ultrasonicwelding utilizing a stitch-weld method forming successive welds betweenthe inner and the outer layers. Further, the present invention alsoprovides a method and apparatus for joining multilayers of similarmaterials.

[0045] It should be realized, however, that the foregoing specificembodiments have been shown and described for the purposes ofillustrating the functional and structural principles of the inventionand is subject to change without departure from such principles.Therefore, this invention includes all modifications encompassed withinthe scope of the following claims.

1. A method of joining multiple layers of materials comprising the stepsof: clamping first, second and third layers of material together betweena sonotrode and an anvil, wherein the first layer is adjacent thesonotrode; forming a weld primarily between the first and second layers;unclamping the first, second and third layers; rotating and clamping thefirst, second and third layers of material together between thesonotrode and the anvil wherein the third layer is adjacent thesonotrode; forming a weld primarily between the second and third layerssuch that the first second and third layers are joined with welds fromalternating sides.
 2. A method of joining multiple layers of materialsto form a multi-layer member comprising the steps of: placing first,second and third layers in a layered relationship; clamping the first,second and third layers together in the layered relationship between ananvil and a sonotrode wherein the sonotrode engages the first layer;ultrasonically welding together at least the first and second layers;unclamping the first, second and third layers and rotating the sonotrodeand the anvil such that the sonotrode is positioned adjacent the thirdlayer and the anvil is positioned adjacent the first layer; clamping thefirst, second and third layers together in the layered relationshipbetween the anvil and the sonotrode wherein the sonotrode engages thethird layer; ultrasonically welding together at least the second and thethird layers such that upon completion of the weld, the first, secondand third layers form a joined together multi-layer member having weldsapplied from both sides of the multi-layer member. 3.A method as setforth in claim 2 including the step of alternately forming welds onopposite sides of the multi-layer member.
 4. A method as set forth inclaim 2 including the step of offsetting the welds applied from bothsides of the multi-layer member.
 5. A method as set forth in claim 2wherein the step of ultrasonically welding the layers includes formingthe weld primarily between the material of the layer in contact with thesonotrode and the material of the layer adjacent the material of thelayer in contact with the sonotrode.
 6. A method as set forth in claim 2wherein the step of ultrasonically welding together at least the firstand second layers includes forming the weld primarily between the firstand second layers and forming at least a partial weld between the secondand third layers.
 7. A method as set forth in claim 6 including the stepof providing additional layers and wherein the step of ultrasonicallywelding together at least the first and second layers includes the stepof continuing to apply ultrasonic energy such that the weld progressesinward from the interface of the first and second layers to theinterfaces of additional layers.
 8. A method as set forth in claim 2wherein the method includes providing additional layers wherein the weldpenetrates inward from the first layer adjacent the sonotrode througheach of the layers to the layer adjacent the anvil.
 9. A method as setforth in claim 2 including the step of forming the weld formed on thethird layer of the multi-layer member opposite the weld formed on thefirst layer of the multi-layer member.
 10. A method of ultrasonicallybonding first, second and third layers of material to form a multi-layermember comprising: providing at least two layers formed of aluminum andat least one layer formed of magnesium; arranging the layers of aluminumand the layer of magnesium to form a multi-layer member such that thelayer of magnesium is sandwiched between the layers of aluminum;clamping the magnesium layer between the aluminum layers; forming a weldbetween the aluminum layer in contact with a sonotrode and the magnesiumlayer; rotating at least one of the sonotrode and the multi-layer membersuch that the opposite side of the multi-layer member engages thesonotrode; and forming a weld between the second aluminum layer and themagnesium layer.
 11. An ultrasonic welding apparatus for use in bondingmultiple layers of material comprising: a frame, said frame including abase, a column and a head, said column connecting said base to saidhead, wherein said column, base and head combine to form a C-shapeframe, said C-shape frame including a throat; an anvil attached to thebase portion of said C-shape frame; an ultrasonic welding deviceattached to the head portion of said C-shape frame, said ultrasonicwelding device including a sonotrode; a power cylinder secured to saidhead, said power cylinder engaging said sonotrode and operative to drivesaid sonotrode into engagement with a workpiece and hold the workpiecebetween the sonotrode and the anvil; a transducer operative to vibratethe sonotrode to perform the bonding operation; and a robot connected tosaid C-shape frame, said robot including an arm operative to move andreposition said C-shape frame and correspondingly said ultrasonicwelding device.
 12. An ultrasonic welding apparatus for use in bondingmultiple layers of material comprising: a frame, said frame including abase, a column, and a head, said column connecting said base to saidhead, and said column, base and head combining to form a C-shape frame,said C-shape frame including a throat; a first ultrasonic welding deviceattached to said head of said C-shape frame, said first ultrasonicwelding device including a sonotrode; a second ultrasonic welding deviceattached to said base of said C-shape frame, said second ultrasonicwelding device including a sonotrode, said sonotrode of said secondultrasonic welding device secured to said base of said C-shape frame ina position opposite said sonotrode of said first ultrasonic weldingdevice secured to said head of said C-shape frame.
 13. An ultrasonicwelding apparatus as set forth in claim 12 wherein at least one of saidfirst and second ultrasonic welding devices includes a support bracketsecured to the C-shape frame; and said sonotrode is slidably secured bysaid support bracket.
 14. An ultrasonic welding apparatus as set forthin claim 12 wherein at least one of said first and second ultrasonicwelding devices includes a power cylinder to drive said sonotrode in areciprocal manner on said C-shape frame.
 15. An ultrasonic weldingapparatus as set forth in claim 12 wherein both of said first and secondultrasonic welding devices include a power cylinder to drive therespective sonotrodes in a reciprocal manner on said C-shape frame. 16.An ultrasonic welding apparatus comprising: an ultrasonic weldingassembly including a sonotrode and a transducer operative to vibratesaid sonotrode to perform a welding operation; an arm assembly, said armassembly including at least one link member supported on a frame andcoupled to a drive unit, said arm assembly connected to and supportingsaid ultrasonic welding assembly, said arm assembly operative to movesaid ultrasonic welding assembly into a first, engaged position whereinsaid sonotrode contacts a first workpiece; an anvil, said anvil attachedto a support member, said support member mounted to a frame member andoperative to move said anvil into a first engaged, position wherein saidanvil contacts a second workpiece; and a controller, said controllercontrolling said arm assembly and said anvil, wherein said controllersends a signal to said arm assembly and said anvil to clamp said firstand second workpieces between said sonotrode and said anvil.
 17. Anultrasonic welding apparatus for welding flange members of multipleworkpieces comprising: an anvil, said anvil mounted on a frame; asonotrode, said sonotrode including a sonotrode tip, said sonotrodeoperative to move between a first disengaged positioned and a secondengaged position, wherein said sonotrode engages one of said flangemembers and clamps said flange members between said sonotrode and saidanvil; a control unit said sonotrode, said control unit sending a signalto said sonotrode to move said sonotrode from said first disengagedpositioned to said second engaged position.
 18. An ultrasonic weldingapparatus as set forth in claim 17 wherein said anvil is mounted formovement on said frame between a first disengaged positioned whereinsaid anvil is spaced from said flange members and a second engagedposition wherein said anvil engages one of said flange members.
 19. Anultrasonic welding apparatus as set forth in claim 18 wherein saidsonotrode is supported on said frame by a linkage assembly, said linkageassembly including an actuator operative to move said sonotrode intosaid second, engaged position.
 20. An ultrasonic welding apparatus asset forth in claim 17 wherein said anvil is connected to an arm member,an actuator coupled to said arm member operates to move said anvilbetween a first, disengaged position and a second, engaged position. 21.A method for welding the flanges of multiple members, the flangesextending at an angle from the multiple members, comprising the stepsof: providing first and second members, each of the first and secondmembers having a flange extending outwardly therefrom; placing the firstand second members in a support fixture such that the respective flangesof the multiple members are each positioned adjacent one another;clamping the flanges between an anvil and a sonotrode of an ultrasonicwelding device; and energizing a transducer to vibrate the sonotrode tointroduce vibratory energy into the flanges to form a weld between therespective flanges of the multiple members.
 22. A method of joiningmultiple layers of material comprising the steps of: clamping multiplelayers of material between a sonotrode and an anvil, wherein thesonotrode is adjacent a first outer layer; forming a weld between atleast the first outer layer and an inner layer adjacent the first outerlayer; clamping the multiple layers of material between a sonotrode andan anvil wherein the sonotrode is adjacent a second outer layer; andforming a weld between at least the second outer layer and an innerlayer adjacent the second outer layer.
 23. A method of joining multiplelayers of material as set forth in claim 22 including: unclamping thesonotrode and the anvil from the multiple layers after the weld isformed between at least the first outer layer and the inner layeradjacent the first outer layer; and rotating at least one of thesonotrode and the multiple layers of material prior to the step ofclamping the multiple layers of material between the sonotrode and theanvil wherein the sonotrode is adjacent the second outer layer.
 24. Amethod of joining multiple layers of material as set forth in claim 22,including the steps of using a first ultrasonic welding device toperform the step of clamping the multiple layers of material between asonotrode and an anvil wherein the sonotrode is adjacent the first outerlayer; and using a second ultrasonic welding device to perform the stepof clamping the multiple layers of material between a sonotrode and ananvil wherein the sonotrode is adjacent the second outer layer.
 25. Amethod of joining multiple layers of material as set forth in claim 22including the steps of clamping the multiple layers of material betweena first ultrasonic welding device and a second ultrasonic weldingdevice; vibrating a sonotrode of the first ultrasonic device whileholding a sonotrode of the second ultrasonic device stationery to form aweld between at least the first outer layer and the inner layer adjacentthe first outer layer; and vibrating the sonotrode of the secondultrasonic device while holding the sonotrode of the first ultrasonicdevice stationery to form a weld between at least the second outer layerand the inner layer adjacent the second outer layer.
 26. A method ofjoining multiple layers of material as set forth in claim 25 includingthe step of unclamping the first ultrasonic device and the secondultrasonic device from the multiple layers of material after the step offorming a weld between at least the first outer layer and the innerlayer adjacent the first outer layer; repositioning the first ultrasonicdevice and the second ultrasonic device on the multiple layers ofmaterial; and clamping the multiple layers of material between the firstultrasonic device and the second ultrasonic device prior to the step ofvibrating the sonotrode of the second ultrasonic device to form a weldbetween at least the second outer layer and the inner layer adjacent thesecond outer layer.
 27. A method of joining multiple layers of materialcomprising the steps of: providing at least three layers, the layersincluding outer layers surrounding at least one inner layer; using anultrasonic welding device to form a weld extending inwardly from one ofthe outer layers to the at least one inner layer; and using anultrasonic welding device to form a weld extending inwardly from theother outer layer toward the at least one inner layer.
 28. A method ofjoining multiple layers of material as set forth in claim 27 includingthe step of forming the weld between the at least one inner layer andthe respective outer layer such that each weld extends to the oppositeouter layer.
 29. A method of joining multiple layers of material as setforth in claim 27 including the step of forming the welds extendinginwardly from the outer layers to a depth such that the welds overlapthe weld from the opposite outer layer.
 30. A method of joining multiplelayers of material as set forth in claim 27 including the step offorming the welds to a depth wherein the welds extending inwardly fromopposite outer layers do not overlap the weld from the opposite outerlayer.
 31. A method of joining multiple layers of material as set forthin claim 27 including the step of forming the welds extending inwardlyfrom each of the outer layers across from one another.
 32. A method ofjoining multiple layers of material as set forth in claim 27 includingthe step of simultaneously forming the welds extending inwardly fromeach of the outer layers.
 33. A method of joining multiple layers ofmaterial as set forth in claim 27 including the step of alternatelyforming the welds extending inwardly from each of the outer layers.